Collaborative Research: Measurement and Modeling of Air Entrainment and Ash Distribution in Weak Volcanic Plumes

2010年冰岛Eyjafjallajökull火山爆发导致空中交通中断数周，经济损失超过10亿美元。用于预测火山灰云的大小、位置和火山灰浓度的模型的准确性受到限制，加剧了这种破坏。2010年之前的航空业政策是避免在飞行期间出现火山灰，现有的模型预测，火山灰羽流覆盖了欧洲大部分地区。这给预报员带来了新的挑战，因为在复杂的流动情况下，无法准确估计火山灰进入云层的速度。这个速率通常是由火山上方羽流的高度决定的，但由于许多因素，包括喷发条件、大气特性和当地风速，它会有很大的变化。因此，迫切需要为现实情况发展改进的模型。传统的羽流模型假设在平静的大气中流动，但羽流被不同尺度湍流的垂直交叉流显著地改变。虽然在一些模型中考虑了横向流动，但其精度仍然相当粗糙。这项研究将提高对分层交叉流中的火山羽流的理解，这将有助于预测危险火山灰云的扩散。先进的实验技术将用于测量实验室规模羽流的流量。这些结果将直接纳入最先进的分析模型，该模型将更准确地量化火山规模的火山灰密度分布。此外，这项研究将在俄勒冈科学与工业博物馆（OMSI）通过小规模的动手实验室演示向广大公众展示。

The 2010 eruption of Eyjafjallajökull volcano in Iceland resulted in weeks of air traffic disruption and more than a billion dollars of economic losses. The disruption was exacerbated by limitations in the accuracy of models used to forecast the size, location, and ash concentration of the cloud. The pre-2010 airline industry policy was to avoid any volcanic ash during flight, and existing models predicted that the plume covered much of Europe. This has provided a new challenge to forecasters, as the rate that ash is fed into the cloud cannot be accurately estimated in complex flow situations. This rate is usually determined from the height of the plume above the volcano, but it can vary significantly due to many factors, including eruptive conditions, atmospheric properties, and local wind speeds. Hence, there is a vital need to develop improved models for realistic conditions.Traditional plume models assume flow in a calm atmosphere, but plumes are significantly modified by perpendicular cross flows with varying scales of turbulence. While cross flow has been considered in some models, the accuracy is still quite crude. This study will develop an improved understanding of volcanic plumes in a stratified cross flow, which will be used to aid in forecasting the dispersal of hazardous ash clouds. Advanced experimental techniques will be used to measure the flow in a laboratory scale plume. These results will be incorporated directly into a state-of-the-art analytical model, which will more accurately quantify the ash density distribution for volcanic scales. In addition, this research will be presented to the broad public audience through small-scale, hands-on laboratory demonstrations at the Oregon Museum of Science and Industry (OMSI).